Process for maintaining a contact lens

ABSTRACT

The aqueous maintenance solution according to the invention is characterized by the presence of an effective amount of polyethylene glycol 120 methylglucose dioleate.  
     Application: to aqueous maintenance solutions for hard contact lenses.

AQUEOUS SOLUTION FOR MAINTAINING CONTACT LENSES

[0001] The present invention relates generally to an aqueous solutionfor maintaining contact lenses, in particular hard contact lenses.

[0002] Aqueous solutions for maintaining contact lenses generally havethe function of decontaminating and cleaning the lenses.

[0003] To be effective, these solutions need to have a combination ofseveral properties.

[0004] Firstly, they need to ensure effective decontamination of thelenses for a broad spectrum of microorganisms, and effective cleaning ofthe surfaces of the lenses, without their active principles beingabsorbed by the lenses.

[0005] Moreover, in order to simplify the maintenance of lenses, it isdesirable for them to be re-usable directly after soaking in themaintenance solution, i.e. without it being necessary to carry out oneor more rinses with water. In this case, it is particularly important,since the maintenance solution must remain in contact with the user'seye, that this solution is not irritant, is well tolerated and leavesthe lenses comfortable to wear throughout the period of continuous use,generally a day.

[0006] An important factor for the comfort of use of treated lenses isthe viscosity of the maintenance solution. This viscosity should not betoo low or too high. If the viscosity of the solution is too low, thesolution will not wet the surfaces of the lens correctly; the user willperceive the lens as a foreign body in the eye, and if the viscosity istoo high, the solution can give rise to cloudy vision and lead to agreasy feel on the lens, which users find uncomfortable.

[0007] Another important factor for the comfort of use of lenses treatedwith a maintenance solution is the ability of the maintenance solutionto retain a relatively large amount of water on the surfaces of the lenstreated, such that the surfaces of the lens are humidified throughout aprolonged period and the wettability of the surfaces of the lens isretained. This characteristic, which will be denoted hereinbelow as “thehumidity-retaining ability” is an important factor for the user'scomfort. This humidity-retaining ability is a particularly importantfactor in the case of hard contact lenses, which generally have a lowability to retain water on their surfaces.

[0008] In order to improve the wettability of contact lens surfaces, inparticular for hard lenses, it has been proposed to incorporatehydrophilic monomers into the maintenance solutions. However, thesehydrophilic monomers generally have the drawback of affecting the otherphysical properties of the lenses.

[0009] To solve this problem it has also been proposed to incorporatewetting polymers into the maintenance solutions, but the action of thesepolymers is weak and disappears rapidly.

[0010] To overcome the abovementioned drawbacks, document WO95/00616proposes adding to the maintenance solutions a water-solublepoly(ethylene oxide) which is a star polymer containing a hydrophobiccore having at least three carbon atoms and at least three hydrophilicpoly(ethylene oxide) chains (arms) attached to the core. In addition,the star polymers in document WO95/00616 must not contain hydrophobicarms attached to the core.

[0011] In a preferred embodiment of document WO95/00616, a secondsurfactant polymer component, a cationic cellulose polymer, is added tothe maintenance solution. This cationic component complexes with thepoly(ethylene oxide) star polymer and the complex formed is stronglyadsorbed onto the surface of the lenses.

[0012] Although the maintenance solutions of document WO95/00616 aresatisfactory, it would be desirable to have available maintenancesolutions which afford the contact lens wearer even better comfort.

[0013] The object of the present invention is thus to provide amaintenance solution for contact lenses, in particular for hard contactlenses, which overcomes the abovementioned drawbacks.

[0014] The subject of the present invention is, more particularly, amaintenance solution as defined above, which gives treated lensesimproved humidity-retaining ability.

[0015] The subject of the present invention is also a maintenancesolution as defined above, which is easy to use, in particular whichallows treated lenses to be used directly, i.e. without rinsing, andmakes the treated lenses comfortable for the user to wear.

[0016] The aims listed above are achieved, according to the presentinvention, by providing an aqueous maintenance solution for contactlenses, in particular hard contact lenses, characterized in that itcomprises an effective amount of polyethylene glycol 120 methylglucosedioleate of formula:

[0017] in which x+y=120.

[0018] The incorporation of polyethylene glycol 120 methylglucosedioleate into the maintenance solution not only increases thewettability of the lenses by the maintenance solution but alsoappreciably improves the humidity-retaining ability of the treatedlenses. In addition, the maintenance solutions according to theinvention make the treated lenses particularly comfortable for the user.

[0019] Preferably, the amount of polyethylene glycol 120 methylglucosedioleate present in the solution is between 0.05 and 5% by weight,better still between 0.1 and 2% by weight, relative to the total weightof the aqueous maintenance solution.

[0020] As is well known, the aqueous maintenance compositions accordingto the invention comprise a decontaminating agent. This decontaminatingagent, generally an antimicrobial agent, is well known in the art andcan consist of a single compound or a mixture of several compounds.Compounds which are useful as decontaminating agents can be any knowncompounds which are useful as decontaminating agents in aqueousmaintenance solutions for contact lenses.

[0021] Among these compounds, mention may be made of chlorhexidine (1,1′-hexamethylenebis[5-(p-chlorophenyl)biguanide]) or water-soluble saltsthereof, such as chlorhexidine gluconate; polyhexamethylene biguanide (ahexamethylene biguanide polymer also known under the namepolyaminopropyl biguanide) or water-soluble salts thereof, such aspolyhexamethylene biguanide hydrochloride sold under the trade nameCosmocil CQ® (ICI Americas Inc.); alkylammonium halides, in particularalkyltrimethylammmonium bromides such as tetradecyltrimethylammoniumbromide, dodecyltrimethyl-ammonium bromide, hexadecyltrimethylammoniumbromide (cetrimonium bromide) sometimes known as “Cetrimide”;benzalkonium halides such as benzalkonium chloride; polymeric quaternaryammonium salts; and mixtures of these compounds.

[0022] The recommended decontaminating agents according to the inventionare polyaminopropyl biguanide and the water-soluble salts thereof, inparticular the product sold under the brand name Cosmocil CQ®, andalkylammonium bromides, in particular cetrimonium bromide, and mixturesthereof.

[0023] A decontaminating agent which is particularly preferred accordingto the invention is a mixture of polyhexamethylene biguanidehydrochloride (Cosmocil CQ®) and cetrimonium bromide.

[0024] The amount of decontaminating agent in the maintenance solutionaccording to the invention is an effective amount, i.e. an amountsufficient to decontaminate lenses. In general, the amount ofdecontaminating agent present in the maintenance solution according tothe invention is from 10⁻⁶ to 5% by weight, preferably 0.01 to 0.05% byweight, relative to the total weight of the maintenance solution.

[0025] Preferably, the maintenance solutions according to the inventioncontain an effective amount of one or more nonionic surfactants. Amongthese nonionic surfactants, mention may be made of fatty acid esters ofpolyethylene glycol, for example of coconut oil, polysorbates,polyoxyethylene ethers and polyoxypropylene ethers of higher alkanes(C₁₂—C₁₈). Examples of the above nonionic surfactants comprisepolysorbate 20 (sold under the brand name Tween 20®), polyoxyethylenelauryl ether (Brij® 35), polyoxyethylene (40) stearate (Myrj® 52),polyoxyethylene (25) propylene glycol stearate (Atlas® G 2612).

[0026] A particularly recommended class of nonionic surfactantscomprises poly(oxypropylene)-poly(oxyethylene) adducts ofethylenediamine and poly(oxyethylene)-poly(oxypropylene) block polymers.

[0027] The preferred nonionic surfactants arepoly(oxyethylene)-poly(oxypropylene) block polymers.

[0028] The maintenance solutions according to the invention generallycontain from 0.01 to 15% by weight of nonionic surfactant relative tothe total weight of the composition, preferably from 0.05 to 1% byweight.

[0029] Preferably also, the recommendedpoly(oxyethylene)-poly(oxypropylene) block polymer nonionic surfactantis present in the maintenance solution in an amount such that the weightratio between this recommended nonionic surfactant and the polyethyleneglycol 120 methylglucose dioleate is about 1:2.

[0030] Although this is not preferred, the maintenance solution can alsocomprise cationic and/or amphoteric surfactants conventionally used inmaintenance compositions for contact lenses, in the usual proportions.

[0031] The maintenance solutions according to the invention preferablyalso comprise one or more standard agents for modifying the viscosity.These viscosity-modifying agents are well known and comprisewater-soluble cellulose polymers such as hydroxyethyl- or hydroxypropylcellulose, carboxymethyl cellulose, polyvinylpyrrolidone andpoly(acrylic acids). The preferred viscosity-modifying agents arecellulose polymers and in particular hydroxyethyl cellulose.

[0032] The viscosity-modifying agent is used in the usual amounts,generally from 0.01 to 4.0% by weight, or less, relative to the totalweight of the solution.

[0033] Besides the polyethylene glycol 120 methylglucose dioleate, themaintenance solutions according to the invention generally contain otherwetting agents conventionally used in maintenance solutions for contactlenses, such as poly(oxyethylene) glycols. These wetting agents aregenerally present in a proportion of from 0.5 to 5%, preferably 1 to 2%by weight relative to the total weight of the solution.

[0034] Preferably also, the wetting agent of poly(oxyethylene) glycoltype is present in the maintenance solution in an amount such that theweight ratio between this recommended wetting agent and the polyethyleneglycol 120 methylglucose dioleate is about 1:1.

[0035] In general, the maintenance solutions according to the inventioncomprise one or more sequestering agents (or chelating agents), inparticular for sequestering calcium and magnesium ions, in an amountwhich can be up to about 2% by weight relative to the total weight ofthe solution. Among the sequestering agents which can be used in thesolutions of the invention, mention may be made ofethylenediaminetetraacetic acid (EDTA) and its salts, in particular itssodium salt, polyphosphate complexes such as sodium hexametaphosphate,sodium pyrophosphate and sodium tripolyphosphate, gluconic acid, citricacid and tartaric acid and their salts, in particular their sodiumsalts. The preferred sequestering agent is the sodium salt of EDTA.

[0036] The maintenance solutions of the invention also generally containa buffer. Among the buffers which can be used in the maintenancesolution according to the invention, mention may be made of phosphatessuch as Na₂HPO₄, NaH₂PO₄ and KH₂PO₄, borate buffers such as boric acid,sodium borate, potassium tetraborate or potassium metaborate, ormixtures of these buffers. A recommended buffer is a mixture ofmonosodium phosphate and disodium phosphate. The amount of buffer usedis generally between 0.05 and 2.5% by weight, preferably between 1 and2% by weight, relative to the total weight of the solution.

[0037] Generally, the tonicity of the aqueous maintenance solutionsaccording to the invention is adjusted by adding a standard tonicityagent, such as sodium chloride or a glycerol solution. The preferredtonicity agent is sodium chloride.

[0038] The maintenance solutions according to the invention can alsocontain, in the usual amounts, any other ingredients conventionally usedin maintenance solutions for contact lenses.

[0039] By way of example of another ingredient which can be incorporatedinto the maintenance solutions according to the invention, mention maybe made of germicidal agents such as thimerosal, sorbic acid,1,5-pentanediol and phenylmercuric salts of alkyl thioethanolamines.Such additional germicidal agents are described in document EP-0 180309.

[0040] Although the description hereinabove refers mainly todecontaminating and cleaning solutions, the compound polyethylene glycol120 methylglucose dioleate can advantageously be used in othermaintenance solutions for contact lenses, such as storage and soakingsolutions.

EXAMPLES

[0041] An aqueous maintenance solution according to the invention,having the following composition, was prepared: Polyaminopropylbiguanide 0.001 g (Cosmocil CQ ® 20% solution) (i.e. 0.0002 g of activeprinciple) Cetrimonium bromide 0.015 g Hydroxyethyl cellulose 0.500 gPolyethylene glycol 120 methylglucose dioleate 1.200 gPoly(oxyethylene)-poly(oxypropylene) block 0.500 g polymer (Poloxamer)Disodium EDTA 0.065 g Polyoxyethylene glycol (Macrogol) 1.200 g Bufferof monosodium phosphate, 2 H₂O and 2.050 g disodium phosphate, 12 H₂OSodium chloride 0.160 g Demineralized water qs 100 ml

[0042] The above maintenance solution was compared with commercialmaintenance solutions. In particular, the humidity-retaining ability ofthe solutions was determined by working in the following manner.

[0043] Dry, hard contact lenses are weighed and are then immersed ineach of the test solutions, removed and drained. Each of the lenses isreweighed and the amount of each solution deposited on each lens isdeduced therefrom. The solutions deposited are left to evaporate for twohours, the lenses are reweighed and the amount of components remainingon them is determined. The difference between the weight of solutioninitially deposited on the lenses and the weight of the componentsremaining on them after two hours of evaporation is an indication of thehumidity-retaining ability of the solution. TABLE I Commercialmaintenance solutions Example Boston ® Solocare ® 1 Simplicity HardTotalcare ® pH 7.20 7.26 7.51 7.10 Viscosity-Pa.s × 10⁻³ (LVI 10 31 1558 30 t/min at 20° C.) Density 1.016 1.010 1.007 1.010 Weight ofsolution remaining 0.0067 0.0048 0.0042 0.0048 on the lens after soakingand draining (g) Weight of components 0.0006 0.0002 0.0008 0.0005remaining on the lens after evaporation of the solution (g) ΔP 0.00610.0046 0.0034 0.0043

[0044] The results show that the maintenance solution of the exampleshows a 32.6%, 79.4% and 41.8% improvement in the humidity-retainingability when compared with commercial solutions.

[0045] The ocular tolerance conferred by the various solutions accordingto the invention, as well as “blank” solutions and solutions accordingto Examples 6C and 14A of document WO95/00616 was determined.

[0046] Besides the solution of Example 1, the test solutions were asfollows:

[0047] Comparative Example A: Solution of Example 1 without GlucamateDOE 120

[0048] Comparative Example B: Solution of Example 1 with 0.1% by weightof Glucam® E 20 instead of Glucamate DOE 120

[0049] Comparative Example C: Solution of Example 1 with 1.2% by weightof Glucam® E 20 instead of Glucamate DOE 120

[0050] Comparative Example D: Solution of Example 1 with 3% by weight ofGlucam® E 20 instead of Glucamate DOE 120

[0051] Comparative Example E: Solution of Example 6C of documentWO95/00616 (0.3% Glucam® E 20)

[0052] Example 2 Solution of Example 6C of document WO95/00616 in whichthe Glucam® E 20 was replaced by 0.3% by weight of Glucamate DOE 120

[0053] Example 3: Solution of Example 6C of document WO95/00616 in whichthe Glucam® E 20 was replaced by 1.2% by weight of Glucamate DOE 120

[0054] Comparative Example F: Solution of Example 14A of documentWO95/00616 without Glucam® E 20 (contains a cationic surfactant- PolymerJR-30M)

[0055] Comparative Example G: Solution of Example 14A of documentWO95/00616 with 0.02% by weight of Glucam® E 20

[0056] Example 4: Solution of Example 14A of document WO95/00616 inwhich the Glucam® E 20 was replaced by 0.02% by weight of Glucamate DOE120.

[0057] The ocular tolerance was determined by direct instillation of thesolutions into the eyes of a tester, who was asked if he or sheexperienced a sensation of eye discomfort.

[0058] The results are indicated in Table II below. TABLE II OcularExample No. tolerance A X B X C X D X E X F X G X 1 ◯ 2 ◯ 3 ◯ 4 ◯

[0059] The solution of Example 1 was used by 80 contact lens wearers fora period of 180 days, with medical monitoring.

[0060] Repeated bimicroscopic observations of the wearers' eyes revealedno manifestation of intolerance to the solution.

[0061] Furthermore, the results with regard to the wettability,scratches and protein deposits observed by the investigators on thesurface of the lenses show that they are well preserved by themaintenance solution.

[0062] Lastly, when asked about the efficacy of maintenance, the comfortwhen inserting the lenses, the comfort at the end of the day and ease ofuse of the maintenance solution of Example 1, 96% of the individualstested said that they were satisfied.

[0063] The addition of polyethylene glycol 120 methylglucose dioleate tomaintenance solutions for contact lenses, in particular hard contactlenses, leads to solutions which make contact lenses more comfortable towear by virtue, in particular, of improving the humidity-retainingability of these solutions on lenses.

[0064] The combination of polyethyleneglycol 120 methylglucose dioleateand a nonionic surfactant proves to be particularly advantageous forobtaining a maintenance solution which is better tolerated by users.

1. An aqueous maintenance solution for contact lenses comprisingpolyethylene glycol 120 methylglucose dioleate of formula:

in which x+y =120.
 2. The aqueous maintenance solution of claim 1 ,wherein the concentration of polyethylene glycol 120 methylglucosedioleate is between 0.05 and 5% by weight relative to the total weightof the solution.
 3. The aqueous maintenance solution of claim 1 furthercomprising a decontaminating agent.
 4. The aqueous maintenance solutionof claim 3 , wherein the decontaiminating agent is selected from thegroup consisting of chlorhexidine and the water-soluble salts thereof;polyhexamethylene biguanide and the water-soluble salts thereof;alkylammonium halides; benzalalkonium halide; quaternary ammonium salts;and mixtures thereof.
 5. The aqueous maintenance solution of claim 4 ,wherein the decontaminating agent is a mixture of polyhexamethylenebiguanide or a water-soluble salt thereof and one or more alkylammoniumhalides.
 6. The aqueous maintenance solution of claim 5 , wherein thealkylammonium halide is cetrimonium bromide.
 7. The aqueous maintenancesolution of claim 3 , wherein the decontaminating agent represents from10⁻⁶ to 5% by weight relative to the total weight of the solution. 8.The aqueous maintenance solution of claim 7 , wherein thedecontaminating agent represents from 0.01 to 0.5% by weight relative tothe total weight of the solution.
 9. The aqueous maintenance solution ofclaim 1 , further comprising at least one surfactant chosen from thegroup consisting of nonionic, cationic and amphoteric surfactants. 10.The aqueous maintenance solution of claim 1 , wherein the surfactantconsists of one or more nonionic surfactants.
 11. The aqueousmaintenance solution of claim 10 , wherein the nonionic surfactant is apoly(oxyethylene)-poly(oxypropylene) block polymer.
 12. The aqueousmaintenance solution of claim 9 , wherein the surfactant represents 0.01to 15% by weight relative to the total weight of the composition. 13.The aqueous maintenance solution of claim 12 , wherein the surfactantrepresents 0.05 to 1% by weight relative to the total weight of thecomposition.
 14. The aqueous maintenance solution of claim 1 , furthercomprising water-soluble cellulose polymer.
 15. The aqueous maintenancesolution of claim 1 , further comprising a sequestering agent.
 16. Theaqueous maintenance solution of claim 15 , wherein the sequesteringagent comprises a compound selected from the group consisting ofethylenediaminetetraacetic acid, gluconic acid, citric acid, tartaricacid, the salts of these acids, and polyphosphate complexes.
 17. Theaqueous maintenance solution of claim 1 , further comprising a buffer.18. The aqueous maintenance solution of claim 17 , wherein the buffer isselected from the group consisting of phosphate buffers, borate buffers,and mixtures thereof.
 19. The aqueous maintenance solution of claim 1 ,further comprising a tonicity agent.
 20. An aqueous maintenance solutionfor contact lenses comprising: polyethylene glycol 120 methylglucosedioleate of formula:

in which x+y=120; a decontaminating agent; a surfactant; a sequesteringagent; and a buffer.